In this specification the term road marking means any indicia applied to the surface of a road to visually provide important information such as the location of lanes to users of a road. Road markings generally are painted onto the road surface however they can also be in many other forms such as thermoplastic tapes, molten thermoplastic sprays, extrusions and many other specialized paints.
The prior art describes methods of measuring road marking thicknesses using lasers and detecting the reflective laser beam off of markings and the surrounding road surface. The difficulties with the techniques described and patented in the prior art is that the road itself can often times be extremely rough and pitted leading to erroneous readings and secondly the painted line itself usually contains highly reflective material such as glass beads which are designed to reflect light and will also produce erroneous readings when measuring the thickness of the road markings.
Therefore there is a need for an efficient, quick and accurate method of measuring road markings that overcome the deficiencies found in the prior art.